The Mars rover Spirit project has been going very well for NASA, but one of Spirit's front wheels has stopped working.
Researchers believe that the motor that rotates the wheel is no longer
working. The motors that rotate the wheels have worked much
longer than the initial mission expected, which may be a reason one of
the wheels has failed. The same wheel had problems before, when it started drawing too much current on the Red Planet. Engineers would temporarily disable the wheel and occasionally run the rover backwards to counter the problem.

Spirit is again dragging the wheel as it tries to reach a position
where it can get as much sunlight as possible during winter, but
although the point of minimum sunshine is more than 100 days away,
there is already only enough to power about one hour of driving on flat
ground per day, JPL said.

The Spirit landed on Mars in January of 2004, and has done a great job gathering information for NASA.

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